Percussion fuse



M.l BIRKIGT 2,079,394

PERCUSS ION FUSE Filed Nov. l5, 1955 t l 1mb# l i y f //)ll f I ffii Patented May 4, 1937 Application November I5, 1935, Serial No. 50,048

In Belgium October 14, 1935l consists in arranging theiuse in such manner that it includes means for locking the strikerina fixed position with respect tothe body of the fuserat least as long as the shell has not left they tube of the rearm, `said means being adapted..

tobe automatically broughtout of action by the slowing down oi the shell. as` soon as it leaves said tube.V

Otherfeatures of the present invention shall l result from the followingdetailed description of a specic embodiment thereof.

A preferred embodiment ofthe present inventionwill `be hereinafter described, with reference totheaccompanying drawing, given merely by way of example, and in which:

Fig. lvis an axial sectionalview of an embodiment of a percussionfus'e made according to the present invention;

Figs. 2, 3 and 4 are similar Views of the same fuse showing diiererit characteristic positions of the parts;

Fig. 5. is a ,detail View, on an enlarged scale, of the general arrangement,.in the relative position of the parts corresponding toFig. 2.

According to the present invention, ther percussionl fuse is 'devised in such manner thatits striker is locked Vini` a fixed position with respect to thebodyof the fuse, atleast until the shell leaves the tube 'of the'gunfthis `locking actionI being exertedby. means arranged to be automaticallylbrught out of this locking position by theeflect' of the forces acting on the projectile when thelatter has left the tube .of the rearm. For this purpose, the fuse according to the` present invention is provided with means capable of moving axially with respect to the striker and said means advantageously consist of two axial rings devised-in such manner that, during the transportation -and the handling of the projec# 'tile on Whichf` the fuse is fitted, they occupy Va position in'which'they lock the striker with respe'ct to thel body of the fuse, and that, as soon as the shock of *discharge takes place, both of these rings leave this position andv occupy,' unden the effect of inertia, a second locking position in Y above explained, 1

striker. 1 A

which they stay as long as the projectile is being" moved inside the tube of the gun. n

The sliding piece or ring whieh'isl positioned nearer to"` the body' of the projectile is so d`e Vised, owing to the'provlsion ot 'a friction or other' arrangement; as to 'be kept inlthis second mentioned position against the 'action-of Vall thegforeesY that normally act i upon said?A projectile; -bu't `this arrangementlpermits saidlast mentioned pece or ring to comebackfintothe #first mentioned.

sneu being suddenlyy yss'opped nisideltne tutelar I the gun.

This friction orl otherhelding arrangement can 'advantageouslybeobtained by splitting this j ring longitudinallyfthat is-to sayf parallellyto its axis in such 'manner that it visV tightly yapplied against the inner wall of its housing, or by providing'said-ring withhooking 'means capableV of being automaticallyA released 'ori 'deformed sol as to enter suitable recesses. provided thebody `of the ring; whereby the latter cancome back into' l its initial locking position in an abnormal case such asthat above 'referred to.

On the contrary, thesliding piece or ring which is nearer to the head of the fuse is arranged in such manner that it is free 'toslide in its housing so! that it can automatically vleaveitsloclr ing position-when, after havinglundergone an acceleration in the tube of the gun, the'velocity of the projectile decreasesfas is'Y-well-known,

immediately after said.-projectile having` leftf said tube, whereby theV last mentioned'sliding piece or ring canmove towardth'ehead of the fuse, away from the other ring provided; as

rangement. Y f l' withv a braking or f ctionar- Elements,Y adva tageously balls, 'urged 'byv the effect of: the centrifugal forcev ideveloped by "the rotation of the-"projectile about its-own axis, can then engage into `the interval Ithus formed bel* tweenthe rings inf'su'ch mannerasto release the Ofi course, f-Jthe'present descriptiomfwhen it is stated that'l-the? striken'is"i released-and can'- Withresp'ect to`the1iuseibody,`"of the detonator,

strike the detonator,ithislrelates'f'to a-'relativef' movement.' of these parts#'witl'fif"respect"-lto each l other, vaindincludesthec'ase in which the-striker 50 tive movement beingproducdby Ea displacement,

locked and released iisaid bodytb the system aboi'ledescrib'ed;` w y Preferably said striker or de'tonator is not pro-' Y vided with means, such as a spring, for urging it Y are braked under normal conditions.

in a predetermined direction, so that Vthe part (striker or detonator) which is released by the spreading apart of the balls or the like, is wholly free, on impact, to move toward the other of these two parts (detonator or striker) so as to produce the explosion of the shell.

In the example illustrated by the drawing, the body I of the fuse consists of a hollow metallic piece, carrying, in the usual manner, in line therewith, a base plug or chamber 2 in which are tted the detonator 3 and primer charge 4. Against the open end of said plug 2 and between it anda corresponding shoulder of body I, there is provided a fixed piece 5 having a hole 6 formed in its central part so as to afford a passage for the striker 7, which is guided in said hole B.

'I'he end of this piece 5 which is turned toward the head of the fuse carries a prolonged part forming a cylindrical sleeve 8 the outer diameter of which is smaller than the inner diameter of the recess formed in body I. In this manner, I provide between this sleeve 8 and body I an annular interval in which can be fitted a ring 9 capable of sliding axially in said annular space.

Ring 9 is so devised that its axial displacements For instance itis split at I6 longitudinally and given such a size and shape that it is strongly applied against the inner `wall of its housing.

In line with said-ring 9 I provide, in the same housing, another ring I2, which is capable of sliding freely in both directions, parallelly to the axis of the fuse.

In the space existing between the free edge of sleeve 8 and an enlarged portion I0 of the striker 7, I fit masses, such as balls I I, held against the striker by either one or both of these two rings 9 and I2 (Figs. 1 and 2) as long as these rings are located in adjacent relation to each other. As soon as these two rings are moved away from each other, they make it possible for balls II, or equivalent means, to automatically engage between them under the action of the centrifugal force developed by the rotation of the projectile about its axis, so that striker I is released.

Said striker 'I is provided at its outer end with an enlarged part I3 which fits in a bore of restricted diameter of the head I4 of the fuse, said bore being closed by a lid I5.

The ogive-shaped, frusta-conical, or even cylindrical structure devised as above explained is of a shape corresponding to that of ordinary fuses.

'I'he fuse above described works in the following manner:

In the state of rest, the various movable parts included in the fuse structure occupy the position shown by Fig. 1, that is to say striker I is locked in fixed position with respect to the body of the fuse by balls I I. The latter are prevented from moving laterally away from one another by rings 9 and I2, these rings being applied against each other by the fact that ring 9 is tightly held in its housing. 'I'he projectile can therefore be transported and handled without any danger since the striker is positively prevented from moving axially. The unlocking of said striker necessitates an axial displacement of ring 9, which can take place only under the effect of forces of inertia several hundred of times more important than those brought into play by any accidental shocks or vibrations as the projectile may undergo before the discharge in the tube of the gun or before the time, determined in the construction, at which the striker is to' be released.

After introduction into the tube of the gun, under the effect of the recoil produced by the shock of discharge, inertia moves both of rings 9 and I2 into the position shown by Fig. 2, for which the upper edge of ring 9 is located below balls II. Accordingly, in this position, ring 9 cannot in any way interfere with the subsequent outward displacement of said balls under the effect of the centrifugal force. But, in this position of Fig. 2, ring I2 prevents this outward displacement of balls II.

Rings 9 and I2 occupy this position as long as the projectile is moving under normal conditions inside the tube of the gun and there is no risk of premature explosion inside the gun.

In case of accidental stoppage of the projectile inside the tube, the whole of rings 9 and I2 moves very rapidly toward the front and the striker remains locked in position with respect to the detonator, the parts being immediately brought back into the initial position shown by Fig. 1.

When leaving the gun tube, the projectile undergoes, as it is well known, a certain reduction of its velocity. Ring I Z, which is free to move in its Y housing and which is not directly acted upon by the causes of this decrease of the velocity, keeps moving with the same velocity, that is to say moves in its housing toward the point or head of the fuse. On the contrary, ring 9, which is axially held in its housing by friction remains in a xed position with respect to the projectile and undergoes the same reduction of velocity as the latter. Consequently, the two rings are moved apart from each other and balls II, urged by the centrifugal force, automatically engage into the space thus left between said rings and accordingly release striker 1.

Of course, the time at which balls I I release the striker depends upon the time necessary for ring I2 to release said balls. The time at which the striker is released can therefore be varied by varying the length of the portion h of n'ng I2 that must move past the balls during the frontward movement of said ring (see Figs. 2 and 5).

For the whole of the time during which ring I2 moves forward but balls II have not yet released the striker, these balls move with a helical motion by rolling in contact with the inner wall of ring I2, which is besides given a relative rotary motion with respect to the body of the fuse. Consequently, it will be readily understood that the helicoids described by the balls are always similar to themselves and that the number of turns made by the balls before they can escape radially remains the same for all fuses including similar constituting elements. Therefore all these fuses shall have the same delay to priming after the projectile has left the gun. There will be no risks of premature explosions, which would be particularly dangerous in the case of a gun ring frontward in the direction of the line of flight of an airplane ying at high speed, since the airplaneV preferably made of such a height that, when balls mi II occupy their locking position, they are in contact with the cylindrical surface of ring I2 when the latter occupies its characteristic position shown by Fig. 2. In this case also, by modifying the interval h (Figs. 2 and 5) which `is provided between the point of contact and the adjacent edge of the chamfer, it is possible to adjust in an accurate manner the time of priming of the fuse.

In consequence of the movement of the balls I I away from one another, the striker is released when the projectile is moving along its trajectory, and, on impact, as shown by Fig. 4, said striker penetrates into the detonator due to a recoil or rebounding effect or due to the crushing of the fuse head. 1

Such a fuse therefore meets all the particular requirements above set forth, and, While being very simple in its structure, very easy and cheap to manufacture and of very small size owing to the small number of parts it includes, its safe Working can be relied upon. The small size of this fuse makes it possible, for a projectile of a given size, to increase the eiciency of said projectile, since the charge thereof can be more important.

Furthermore, this fuse is perfectly iiuidtight since its ogive is made of a single piece.

Of course the centrifugal masses which lock the striker and then release it after the projectile has left the gun might, instead of balls, consist of juxtaposed and distinct elements of an Vannular whole of rectangular or circular, or even trapezoidal or triangular, cross section, whereby said elements can engage in a wedge-like fashion between rings 9 and I2 for moving them apart from each other under the effect of the centrifugal force.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and eiiicient embodiments of the present invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

What I claim is:

1. A percussion fuse for a projectile to be red from a gun which comprises, in combination, a hollow fuse body having a cylindrical axial bore therein, a detonator xed in said body at the tail end thereof, a striker axially movable in said bore having a portion of enlarged diameter, a plurality of locking balls in an annular recess in said bore around said striker adapted, when held close to the axis of the fuse, to engage said enlarged portion of the striker so as to lock it axially, two rings fitting slidably in said bore disposed in line with each other in the axial direction of said bore, stops in said bore for limiting the displacements of said rings in both directions respectively, the ring that is closer to the head of the fuse being freely movable in both directions longitudinally of the fuse in said bore and constrained only by said other ring -while the said latter ring is movable towards its fown stop only in response to very high accelerations, such as that produced by the shock of discharge in the gun, and is initially fixed in a position that keeps the ring closer to the head of the fuse applied against its respective stop toward the head of the fuse, said other ring being 'movable only in response to abnormal decelerations such as that produced by the shock caused by the sticking of the shell in the barrel of the gun, said rings being adapted to keep said balls engaged against lsaid enlarged portion of the striker as long as said rings remain in contact with each other, and to release said balls so as to allow them to move away from the striker under the action of a force tending to move them radially as soon as the ring that is closer to the head of the fuse is moved forward and apart from the other by the normal retarding of the velocity of the projectile.

2. A percussion fuse according to claim 1 in which said second mentioned ring, that is to say the ring that is movable only in response to very high accelerations, is a split ring and is so shaped and dimensioned as to be strongly applied against the inner wall of said bore.

3. A percussion fuse according to claim 7 in which said element and said members are provided with means cooperating to force said members away fromeach other in wedge-like fashion as soon as the movement of said members away from each other has been started to a predetermined degree.

4. A percussion fuse according to claim 1 in which the rst mentioned ring, that is to say the ring that is freely slidable in said bore, is provided with a chamfer along the edge thereof that is closer to the other ring, whereby said balls act in a wedge-like fashion to force said rings away from each other, as soon as the movement of said rings away from each other has been started to a predetermined degree.

5. A percussion fuse for a projectile to be iired from a gun which comprises, in combination, a hollow fuse body, two parts, one of which constitutes the detonator and the other the striker of the fuse, in said body, one of said parts being rigidly affixed to the projectile and the other being slidably attached to and movable longitudinally within the hollow fuse body, locking means for said movable part adapted to release it when left free to respond to the action of a force tending to move said means radially, two members movable inside said body disposed behind each other in the axial direction of the fuse, the member that is closer to the head of the fuse being freely movable in both directions longitudinally of the fuse and constrained only by the other member while the said other member is in frictional engagement with an element rigid with the body of the shell so that it is movable only in response to very high accelerations, of the kind of that produced by the shock of the discharge in the gun, said members being adapted to limit the radial movement of said locking means, thereby keeping said means in the. operative locking position as long as said means and members are in contact with each other and to release said means when the member that is closer to the head of the fuse is moved apart `from the other by normal decelerations of the velocity of the projectile, thereby allowing said means to escape from operative locking position into the space so provided between said members.

6. A percussion fuse for a projectile to be fired from a gun which comprises, in combination, a hollow fuse body, two parts, one of which constitutes the detonator and the other the striker of the fuse, in said body, one of said parts being fixed and the other axially movable therein, at least one locking element for said movable part capable of occupying either of two positions, one close to the axis of the fuse and the other at a: greater distance from s'aid axis, said element being adapted, in its rst position, operatively t'o engage 'said movable part and, in its other position, to release said movable part, two members movable inside said body disposed behind each other in the axial direction of the fuse, the member that is `closer to the head of the fuse being freely movable and constrained only by the other member, in both directions longitudinally of the fuse, while the said other member is in frictional engagement with an element rigid with the body of the shell so that it is rearwardly movable with respect to the axisl of the shell only in response to very high acceleration, such as that produced by the shock of discharge in the gun, and said other member having suicient mass to overcome the friction of its said engagement with the element rigid with the body of the shell in response to sudden deceleration, such as that produced by the sticking of the shell in the barrel of the gun, said members adapted to keep said locking element in its rst mentioned position as long as they are in contact with each other and to allow said element to come into its second mentioned position, under the action of the centrifugal force, as soon as one of said members is moved apart from the other.

7. A percussion fuse for a projectile 'to be iired from a gun which comprises, incombination, a hollow fuse body, detonator xed in said body, a striker axially movable therein having a portion of enlarged diameter, a plurality of locking balls in said body around said striker adapted, when kept close to the axis of the fuse, to engage said enlarged portion of the striker so as to lock it axially, two members movable inside said body disposed behind each other in the axial direction of the fuse, the member that is closer to the head of the fuse being freely movable and. constrained only by the other member, in both directions longitudinally of the fuse, While the said other member is in frictional engagement with an element rigid with the body of the shell so that it is movable only in response to very high aecelerations, of the kind of that produced by the shock of the discharge in the gun, said members being adapted to limit theA radial movement of said locking means, thereby keeping said means in the operative locking position as long as said means and members are in contact with each other and to release said means when the member that is closer to the head of the fuse is moved apart from the other by normal decelerations of the velocity of the projectile, thereby allowing said means to escape from operative locking position into the space so provided between said members.

MARC BIRKIGT. 

